DESCRIPTION (Applicant's abstract): Studying brain and behavioral changes associated with memory in food-caching birds may shed more light on the relationship between memory and hippocampal formation. Knowing how environmental pressure has affected the evolution of memory can help us understand how human memory has been evolving. In addition, studying how environmental factors affect hippocampal plasticity may also help us to understand how brain repair may occur after cell death resulting from stroke or similar brain damage. Specific aims of my study are (1) to analyze the effect of unpredictable food on memory and brain morphology in food-caching chickadees by manipulating food supply and (2) to examine the effect of high energetic demands resulting from long winters on memory and brain morphology by comparing birds from high (Alaska) and low (Ohio) latitudes. Comparing caching and non-caching species could provide additional information on the relationship between memory, brain, and ecological conditions. If such conditions have a significant impact on memory and the hippocampus, then we should see changes in food-caching species but not in non-caching species. On the other hand, if such ecological conditions directly affect the brains of all birds irrespective of memory for caches, then both caching and non-caching species should show changes in memory and hippocampal morphology.